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If only there was a bolt on overdrive unit to put behind the ultramatic ...i find that with the new radials (or maybe just from the factory) my speedo says i'm going about 5-7 mph faster than the gps does at about 70-75.

When i had the 288 in and was doing 75 down the highway, it definitely was like driving a boat. All (or most of the) throttle or none.

Speedometers that were 5% or so optomistic were pretty typical of the era. Many of the test reports in the 40s thru the 80s often gave the speedometer error.

Radials also will upset speedo accuracy as they generally have a smaller diameter than the bias-ply tire they replaced.

Dave, in fact that confirms the outstanding quality of Packard. At work we drive all-premium cars (Audi A8, Mercedes S-Class, VW Phaeton, BMW 7 Series), all of them with electronic speedometer and at least a third of them have the same average deviation of approx. +5%, easy to measure when driving in convoy by cruise control or speed limiter. BTW in Germany a positive deviation of 10% + 4 km/h (2.49 mph) is within the limits of statutory regulations.

example: 50 mph + 5 mph (10%) + 2.49 mph = 57.49 mph

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According to this ad, there is one for sale in Pt. Townsend, WA.

packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7721&forum=8

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So if i just bolt a 3 speed with overdrive behind the ultramatic, i should be set to go and have the speed with ultramatic overdrive!

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Ross,

Thanks for the specifics. I'm wondering now what final drive ratios were available in the '48-'50 Packards with 288 cid engines.

It sounds like the 3.54 would really be the ticket especially with a manual trans. Any identifying marks on the differentials or axle tubes on these cars that can help determine the gear ratio installed?

The 288 sounds like a very sound engine. It's interesting to me that it will actually take a bit more rpm than the 327. I always assumed that the 327 was a bored out 288. I never looked up the bore and stroke, but now it sounds as if the the 327 was a "stroked" 288. I'm lazy, but I'll look it up if no one beats me to the answer!

Also, Ross, what is the fuel consumption rate of a fighter jet... or a Packard at 80 mph? And what's your typical fuel mileage at a more sedate 65-70? (Also, of course, is what final drive ratio you are running, whether you have overdrive, what carburetor is installed...)

Thanks for all the input everybody!

EDIT: OK, my trip to specland says the 327 had 3 1/2 in bore, same as 288, but 4 1/4 in stroke, a full half inch longer than the 3 3/4 in 288 stroke, thus, higher piston speed in the 327 and lower safe rpm limit. But you all knew that already, I suppose.